The present invention relates to an optical assembly, and in particular to an optical assembly for steering or directing electromagnetic radiation, such as a laser beam, towards a desired location.
In many optical applications, electromagnetic radiation, such as the beam from a laser source, needs to be directed towards a given target or targets. For example, in many systems a laser beam will need to be directed into an optical fibre for, e.g., delivery elsewhere.
The Applicants have already proposed, e.g., in their UK Patent numbers 2325058 and 2325057, devices and arrangements for coupling electromagnetic radiation, such as laser beams, into or between optical fibres. In these devices, the, e.g., laser source and optical fibre are arranged in close proximity to each other and may be adjusted relative to one another to provide an optimum coupling arrangement.
However, there are situations in which the electromagnetic radiation source, such as a laser, will need to be spaced from the target, such as an optical fibre, that it is to be directed at or into. For example, it may be desirable to include other optical components or elements, such as a modulator or beam combination optics, etc., between the, e.g., laser, source and the input to the, e.g., output optical fibre. In these arrangements it is usually still desirable to accurately align the, e.g., laser beam with the input face of the optical fibre, but this can be more difficult because the beam travels a greater distance in free space before it enters the fibre.
It is therefore known to use various techniques to try to align the electromagnetic radiation and, e.g., fibre. For example, the fibre's position can be adjusted in a similar manner to that described in the Applicants' earlier patents discussed above. Additionally or alternatively the radiation source, e.g., laser, could be mounted in such a way that the pointing direction of its output can be reliably and accurately adjusted. However, this can be difficult to achieve whilst still maintaining a sufficiently rigid mounting for stability purposes and also providing a suitable heat sink (thermal) path for heat dissipation.
It is also known to provide beam steering or tilting arrangements intermediate the source and target (e.g. optical fibre) to, e.g., allow some adjustment or steering of the, e.g. laser, beam towards the target. Such devices commonly comprise coupled mirror pairs whose mirrors can be tilted together or independently to move the position of the output beam. However, this requires additional optical components, with commensurate effects on the cost, size and complexity of the overall system.
In many optical systems the electromagnetic radiation, e.g. laser, beam may also need to be adjusted in size or shape to match it to a particular target, such as an input face of an optical fibre. This can be the case where, e.g., several lasers of different wavelengths are to be combined and input into a single fibre. In such a case, each laser beam may differ in size and/or shape, and it may therefore be desirable to condition the beams before they are input to the fibre to be similar (to look similar to the fibre) in size and shape (and, e.g., to optimise them in size and shape for the fibre). Such beam shaping can be done using a lens, but again this may add complexity and cost to the arrangement.